alert('Windows Popup text');
prompt('Windows Popup Text and return value entered');
confirm('Display ok and Cancel button and return true or false');
<!DOCTYPE html>
<html>
<head>
<title>Java script Demo</title>
</head>
<body>
<h1>Titre niveau 1</h1>
<script>
alert('your javascript here!');
</script>
<script src="js/app.js"></script>
var myVariable;
var myVariable = 10;
var myVariable = "some string"; var myVariable = 'some string'; var myVariable = 'it \'s easy';
var myBolean = 10 > 1;
var myOppositeBolean = !myBolean;
alert(typeof myVariable);
cond1 = 1 > 2 && 2 > 3
cond2 = 1 < 2 | 10 > 1
if(cond1) {
alert('cond1 is true');
} else if(cond2) {
alert ('cond2 is true');
} else {
alert('cond1 and cond2 are false');
}